New national and regional bryophyte records, 31

Abstract

Seasonal patterns in growth and dynamics of 13 epixylic bryophyte species (six liverworts and seven mosses) were studied within permanent plots in the ?ofínský prales old-growth forest in south-eastern Bohemia, Czech Republic. Transparencies were used to record positions and cover of bryophyte colonies within each plot twice a year (in spring and autumn) for periods of 1–4 years. Percentage growth of species populations and growth dynamics of their colonies were analysed in order to identify seasonality in their growth. Establishment of bryophyte colonies and their expansion, as well as pair-wise overgrowth of adjacent colonies of different species were compared in order to identify competitive interactions between bryophyte species. Bryophytes grew faster during the winter season (October–April) than during summer, and the various species did not differ in their percentage growth. The growth dynamics of bryophyte colonies was highly seasonal and the species differed in their dynamics pattern. The expansion and retreat (local extinction) of bryophyte species were greatest in winter, and the stability of colonies was, therefore, higher in summer. Interspecific competition among the species studied appears to be low.     

New national and regional bryophyte records, 28

Abstract

We are grateful to all those who have sent references for inclusion in this list and will be pleased to learn of any publications we have failed to note. Electronic access to all citations in 'Recent Bryological Literature' from RBL 112, and all citations in 'Recent Literature on Bryophytes' from The Bryologist, are available via W3MOST on the TROPICOS website (http://mobot.mobot.org/W3T/Search/mbib.html).     

New national and regional bryophyte records, 37

Abstract

We analyzed the form of the UV-absorption spectra and calculated the bulk UV-absorption capacity of the methanolic extracts (BUVACME) in 15 bryophytes (five liverworts and 10 mosses) from unshaded aquatic habitats of Tierra del Fuego (Argentina). BUVACME was obtained as the area under the absorbance curve (AUC) in several ranges of the UV band to allow comparison with the literature data. Both the spectra form and the AUC values depended on the species considered. The spectra showed either no, one or two defined peaks. The peaks were probably due to phenolic derivatives, which could act as both screening compounds and antioxidants. The different AUCs calculated were highly and significantly correlated, and thus it may be unimportant which of these is used. The AUC values of most liverworts were higher than those of most mosses and in particular, the liverworts Noteroclada confluens and Triandrophyllum subtrifidum showed much higher BUVACMEs than those analyzed in any other bryophyte. Thus, the accumulation of UV-absorbing compounds might often increase protection against UV radiation in liverworts, but rarely in mosses. This is in line with the evolutionary differences between these two groups of bryophytes. Except for the two abovementioned liverwort species, BUVACME of aquatic bryophytes from Tierra del Fuego is not particularly different to that found in bryophytes from other zones of the planet.     

New national and regional bryophyte records, 47

Abstract

The moss Timmia megapolitana is reported new to the British Isles. It occurs in an area of freshwater tidal Salix carr in the Norfolk Broads and differs from the other two species of Timmia in Britain and Ireland in leaf form and anatomy, sexuality and habitat. In the field Timmia megapolitana is most likely to be passed over as Atrichum undulatum, and since access to the area is difficult there is the possibility that it has been present for many years. The habitat and ecology shows a remarkable similarity to that in the Netherlands, the nearest European locality. Rare in Europe, the plant also occurs in Finland, northern Russia and Siberia, regions that provide staging posts and breeding grounds for migratory birds that over-winter in Norfolk.     

New national and regional bryophyte records, 46

Abstract

Bryophyte biomass and diversity vary strongly with altitude in the tropics. Low abundance and low species numbers in lowland rain forests are most likely due to reduced diurnal activity times combined with high nocturnal respiration rates at high temperatures. This may exclude many montane species from the warm lowlands. However, an alternative hypothesis explains the observed pattern, namely a limited desiccation tolerance of montane species, precipitation being more concentrated but less frequent in most lowland forests compared to montane cloud forests. To test this hypothesis, we studied the desiccation tolerance of four montane and four lowland bryophyte species. The effects of prolonged drought were quantified with chlorophyll fluorescence (F_v/F_m) and the extent of electrolyte leakage. Both montane and lowland species survived dry periods of ≧80 days, which far exceeds the duration of dry periods in the wet lowland tropics. We can thus exclude intolerance to long dry spells as an explaination for the absence of the tested montane species in the lowlands. We should continue to focus on other mechanisms to explain the altitudinal gradient of bryophyte abundance and diversity in the tropics, in order to understand this pattern, as well as to predict future trends under climatic warming.